The functional rs4880 alanine-to-valine (C > T) single amino acid change has been found to influence enzyme activity with valine (T) associated with reduced SOD2 activity in human breast cancer and hepatoma cell lines (Sutton et al. 2005; McAteea and Yager 2010); contradictory findings have also been reported (Martin et al. 2009; Bastaki et al. 2006). Here, SOD2 is linked to breast cancer.